1. Field of the Invention
The present invention relates generally to a governor pressure controlling apparatus, and more particularly to a governor pressure controlling apparatus of automatic transmission for vehicles.
2. Description of the Prior Art
Generally, an automatic speed changing position is established according to a vehicle speed in an automatic transmission for vehicles, that is, speed changing is accomplished by governor pressure generated by a governor pressure generator which is changeable according to the vehicle speed. This is clearly represented in FIG. 1 and the formula is as follows:
P= C m r w.sup.2
P: oil pressure PA2 C: coefficient PA2 m: weight of governor valve PA2 r: rotational radius of governor valve PA2 w: angular speed of shaft
The governor pressure is in proportion to square of speed and is sensitive to the vehicle speed as best seen from the abovementioned formula. For example, when the governor pressure is set on the low speed side as shown at curved line 1-- 1 in FIG. 1, the governor pressure is quickly increased according to an increase of vehicle speed and exceeds the controlling oil pressure (line pressure) of the automatic transmission upon high speed of the vehicle, thereby making it difficult for detecting the vehicle speed, and when the governor pressure is set on the high speed side as shown at curved line 1- 2 in FIG. 1, the governor pressure is low. When the vehicle speed is low and there is danger that the vehicle speed may not be detected, so that normally at least two kinds of governor pressure, namely, governor pressure for low and high vehicle speeds is provided. The governor pressure generator is generally arranged at the rear portion of the transmission and an oil pressure control apparatus, fluidically connected to the governor pressure generator via a conduit, is generally arranged at the lower portion or a side portion of the transmission. Therefore, if the conduit connecting the governor pressure generator with the oil pressure control apparatus is short, it becomes advantageous to design and construct the whole governor pressure controlling apparatus.
However, in a conventional governor pressure controlling apparatus, separate governor pressure generates generators disposed on a rotational shaft, for example, when two kinds of governor pressure are employed, two governor pressure generators should be arranged on the rotational shaft, and a conduit provided for transmitting the line pressure to the governor pressure generator and to the oil pressure control apparatus and also two conduits for transmitting two different governor pressures should be connected thereto. When more than three governor pressures are employed, at least four conduits are required.